Molecular and Cell Biology: Exam 4 Review Questions with Answers

Exam 4 Review Questions Previous Material 1. Euchromatin is __________ packed chromatin, heterchromatin is _________packed chromatin. A. densely, loosely B. tightly, densely C. loosely, densely D. condensed, loosely E. magically, delicious The correct answer is Answer C because the euchromatin are the loosely packed chromatin and the heterochromatin are the densely packed chromatin. Answer A is incorrect because it’s the exact opposite for each term. Answer B is incorrect because tightly and densely mean the same thing and euchromatin and heterochromatin aren’t synonyms. Answer D is also incorrect because they are in the wrong slots. Answer E is incorrect because it is a joke and doesn’t make sense! 2. ____________are responsible for the first level of DNA packing in chromatin. A. Chromosomes B. Euchromatin C. Histones D. Heterochromatin The correct answer is C because the histones are actual proteins that help with the packing of chromatin. Answer A is incorrect because chromosomes aren’t responsible for packing chromatin. Answer B and D are refering to different ways to pack the DNA. 3. Which of the following statements if false? A. Transcription is to "copy the same language" while translation is to "copy into a new language" B. Transcription is the copying DNA into a complimentary RNA sequence C. Translation is when a sequence of nucleotides in a mRNA molecule directs the set of amino acids into a protein D. All of the above are true Answer D, all of the statements (A, B, C) are true. Transcription takes place first inside the nucleus and it is the process described in B. Then translation takes place on the rough ER and is the process described in C. 4. Which of the following contains the only 4 basic components of vertebrate ECM? A. Glycosaminoglycans, elastin, fibrous proteins, proteoglycans B. Elastic proteins, laminin, fibronectin, collagen, proteoglycans C. Collagen, fibronectin, glycosaminoglycans, proteoglycans D. All of the above E. None of the above The correct answer is E, none of the above because each of the options contain at least one of the specific forms of either the fibrous proteins or elastic proteins. The basic components are simply gycosaminoglycans, proteoglycans, fibrous proteins, and elastic proteins. 5. Which protein is not a fibrous protein of the extracellular matrix? A. Collagen B. Fibronectin C. Laminin D. Elastin E. None of the above Answer (D) Elastin is a component of the extracellular matrix, but it is not a fibrous protein. Elastin is an elastic protein which allows for stretch and recoiling of the cells. All other answers are fibrous proteins that are tough to structure the ECM. 6. The cytoskeletal system consists of 3 fibrous components including: A. thin filaments, actin, intermediate filament B. actin, tubulin, intermediate filaments C. microtubules, actin, tubulin D. intermediate filaments, actin, myosin E. myosin, thin filaments, microtubules The three components of the cytoskeletal system includes; thin filaments, microtubules, and intermediate filaments. Think filaments consist of the actin family of proteins and microtubules consists of the tubulin family of proteins. 7. Which fibrous component(s) have dynamic instability? A. Thin filaments B. Microtubules C. Intermediate filaments D. A and B* E. B and C Section 2 C. Cytoskeleton and Adhesion.Review: Big picture. Dynamic instability is the coexistence of assembly and disassembly and can switch from growing to shrinking phases. This only occurs in thin filaments and microtubules but not intermediate filaments because they are constructed for long-term use. 8. Which of the following are characteristics of both actin microfilaments and tubulin microtubules? A. Ability to form dimers B. Are found in all eukaryotes C. Have 3 main isoforms (alpha, beta, and gamma) D. All of the above E. Both B and C The correct answer is E because actin filaments and tubulin microtubles are both found in eukaryotes and have the alpha, beta, and gamma isoforms. Answer A is incorrect because actin are monomers that make chains, microtubules are dimers. Since answer A is incorrect, D can't be true. Both B and C are correct on their own but Answer E includes both of them. 9. Rope like filament structures formed from 8 protofilaments twisted together and does not have a molecular motor is a characteristic of what cytoskeleton system? A. Thin Filaments (Chains of few monomers and has a molecular motor) B. Microtubules (Large hollow tubes of many dimmers and this also has a molecular motor) C. Intermediate filaments D. None of the above 10. What are two characteristics of intermediate filaments? A. Polar/ Lack motors B. Structural polarity/Form double helix C. Apolar/ Isoforms D. Lack motors/ Apolar E. Polar/ Motors The correct answer is D, intermediate filaments do not have motors and they are apolar. Answer A is incorrect because it says intermediate filaments are polar, which they aren't and that's what makes them more stable. Answer B is incorrect because intermediate filaments aren't polar at all and they don't form a double helix, those are characteristics of actin. Answer C is incorrect because intermediate filaments lack isoforms. Answer E is incorrect because intermediate filaments don't have motors and they are apolar. 11. Actin structures are assembled and disassembled rapidly, which of the following dictates this assembly and cell function? A. Activity of microtubule organizing center in specific cellular locations B. Location of the cytoskeleton in the cell C. Expression of microfilament associated proteins in specific cellular locations D. All of the above The correct answer is C because the activity and expression of microfilament associated proteins in a specific cellular location dictates the actin assembly and disassembly. Answer A is incorrect because it is referring to the MTOC's which aren't relevant in terms of actin. Answer B is incorrect because location of the cytoskeleton doesn't dictate the fact that it will be assembled and disassembled. Answer D is incorrect because 2 of the answers are incorrect. 12. Which of the following are involved in disassembly of actin filaments? A. Profilin B. Gelsolin C. Cofilin D. B and C Answer D, because profilin is involved in increasing the rate of polymerization and the question is asking about depolymerization. Gelsolin can sever a whole actin filament in half to allow a quicker rate of disassembly of actin filaments and cofilin is responsible for depolymerizing one monomer at a time which allows for reassembly of actin filaments as the cell needs. 13. Which of the following are involved in disassembly of microtubules? A. Stathmin B. Katanin C. Spastin D. B and C Answer D, because stathmin inhibits the nucleation of microtubules while Katanin and Spastin are both responsible for severing alpha and beta tubules. 14. Kinesins and myosins are similar in that they both: (regulation; molecular detail) A. move along microtubules towards the positive end (away from the MTOC) B. have single head(type 1) and double head (type II) designs C. little sequence similarity but remarkable similarities in tertiary structures D. B and C are correct E. all of the above Myosins have the capability of moving either towards the positive or negative ends while kinesins can only move in the positive direction, towards the MTOC. Although they both have the ability to move towards the positive end, myosin moves specifically across microfilaments and kinesins move across microtubules. They both have the single and double head designs and similar tertiary structures. 15. Which molecular motors allow filament intracellular transport on microtubules A. Kinesin B. Myosin C. Dynein D. A and C only E. None of the above (Review: Big Picture) Answer (D) Both Kinesin and Dynein move along microtubules toward or away the microtubule organizing centers. Kinesin moves towards the positive end (away from MTOC) and Dynein move towards the negative ends (toward the MTOC). 16. What is similar between Focal adhesions and Hemidesmosomes? A. They both use Actin or microfilaments B. They both use Intermediate filaments C. They both use anchor proteins D. They both are very stable E. All the Above Focal adhesions are very similar to the hemidesmosomes in the ways that they are composed. The correct answer would be C because both focal adhesions and hemidesmosomes bind anchor proteins to integrins to ECM (Extracellular Matrix) fibrous proteins. However it is what binds to the anchor proteins that are different between the two. Hemidesmosomes used intermediate filaments to bind to anchor proteins and Focal adhesions use microfilaments also known as actin filaments. Also the answer is not D because focal adhesions can be stable, but also used for migration while hemidesmosomes are very stable. 17. What is similar between desmosomes and adherens junctions? A. They both are used for cell to cell comtact B. Anchor proteins are bound to their own cadherins C. A cells cadherins bind to the adjacent cells cadherins D. A and C E. All the above Both desmosomes and Adherin juctions are used in connection two adjacent cells. In desomosomes Intermediate filaments bind to anchor proteins which bind to their own cadherins which bind to the adjacent cells cadherins casing a cell to cell adhesion. In Adheren junctions microfilaments bind to anchor proteins that bind to their own cadherins which then bind ti the adjacent cell’s cadherins. Here the difference is that Adheren junctions use microfilaments and desmosomes use intermediate filaments. 18. Desmosomes are made of ______________________to ensure long term use. A. Actin microfilaments B. Tubulin microtubules C. Centrioles D. Intermediate filaments* E. e.Anchoring proteins Section 2 C. Cytoskeleton and Adhesion. Review: Molecular detail. Desmosomes are made of intermediate filaments and are intended for long-term use. They are meant to to resist shear force and are found in squamous and simple epithelium cells. Intermediate filaments are constructed of 8 protofilaments twisted together. They are formed into strong rope-like filaments to provide cytosol and structural integrity through cell-to-cell junctions, which do not come apart easily. The desmosomes bind intermediate filaments to anchor proteins to their own cadherins, which bind to the adjacent cell’s cadherins. The other fibrous components listed are not strong enough and have dynamic instability so they can easily assemble and disassemble. 19. Which of the following statements in regards to cell adhesion is false? (regulation; big idea) A. all cells of multicellular organisms must adhere to survive B. cells adhere to other cells, ECM, or quite commonly, to both C. it is common for cells that lose their appropriate attachments to undergo anoikis D. all of the above are true Most cells must adhere to survive but a few cells are free. Cells can adhere to each other or to the ECM. Cellular adhesion is critical because for most cells if they lose their adhesions for any amount of time they will undergo anoikis. 20. Which of the following binds intermediate filaments to anchor proteins to integrins to the ECM fibrous proteins? A. Focal Adhesions B. Hemidesmosomes C. Desmosomes D. All of the above Answer B, because focal adhesions bind microfilaments to anchor protein to integrins to ECM fibrous proteins, while desmosomes bind intermediate filaments to anchor proteins to their own cadherins which bind to adjacent cell's cadherins. 21. Hemidesmosomes bind intermediate filaments to _________ to integrins to ECM fibrous proteins a. Anchor proteins b. Cadherins c. Basal lamina d. Microtubules Rationale: Hemidesmosomes bind intermediate filaments to their anchor proteins then to their cadherins which then bind to the neighbor cell’s cadherins to form a tight junction. 22. What are the basic mechanisms of Cell Migration? A. Triggered by signals from outside the cell B. Actin-myosin based movement C. Requires attachments to outside to pull against D. Ability to move all cell content E. All of the above Rationale: In order for a cell to migrate successfully, it much be able to detect outside signal, and use actin-myosin to pull itself and its cell content. It must also be able to attach to the outside to drag. 23. What is the leading edge extension of lamellipodia driven by? A. Actin polymerization B. Microtubule Assembly C. Phosphorylation of Intermediate filaments D. None of the above Answer A, because the cell membrane is physically pushed forward by actin. G-actin adds to the f-actin chain as ATP-actin and then it comes off as ADP-actin. The rate of hydrolysis controls the rate of migration. 24. In Intercellular Diapedesis: A. Chemokines activate endothelial cells to express ICAM-1 and E selectin B. Occurs during the presence of a pathogen or infection C. E-selectin helps to slow down leukocytes casing tight binding D. A and C E. All The above (Review: Molecular detail) Intercellular diapedesis is the response of monocytes and luekocytes in the presence of a pathogen or infection. Cytokines are the ones that are responsible for endothelial activation and expresses ICAM and E selectin. Chemokines have specifity and has the affinity that attracts leukocytes by specific receptors such as IL-8 which attract neutrophils. E selectin does help slow down leukocytes but by tight causing rolling adhesion not tight binding. So the correct answer is B. 25. Which of the following is NOT a component of the extra cellular matrix? A. glycosaminoglycans B. proteoglycans C. fibrous proteins D. elastic proteins E. none of the above Answer: E, all of the above components are part of the extra cellular matrix. The category for this question is review: molecular detail of the extra cellular matrix. Current Material 26. Stem cells in the cell cycle, will differentiate to create which two cells? A. 1 daughter cell with same functions as stem cell B. 1 daughter cell with different function as stem cell C. 2 daughter cells with completely different functions as stem cell D. B and C only E. A and B only A stem cell in the cell cycle will differentiate to give rise to one daughter cell with the same functions and genes as the original stem cell and another daughter cell that will have completely different functions and will attach to the basal lamina of the epithelium. 27. What is a true statement regarding stem cells? A. A stem cell is a cell that is undifferentiated B. Renewing is not a constant process C. Only produces cells that retain a undifferentiated character D. Only produces cells that can undergo multiple paths of differentiation E. Only A, B and D This is because stem cells are cell types that are undifferentiated. The renewing process is always constant so answer B would be false. When stem cells divide they produce both a cell containing an undifferentiated character and one that can differentiate into different types of cells. So both b and C are also false. 28. Which of the following epithelium architecture is incorrect? A. Small intestine – simple columnar B. Blood vessel – simple squamous C. Skin – pseudostratified squamous D. Trachea – ciliated pseudostratified columnar E. All of the above are correct The skin is stratified, forming actual layers, unlike the trachea, which has the appearance of layers but not true layers. 29. What are the four cell types in Small Intestine? A. Absorptive, goblet, enteroendocrine and paneth B. Absorptive, macrophage, goblet and endocrine C. Absorptive, epithelial, endocrine and goblet D. All of the above E. None of the above These four are the four types of cells in the small intestine that helps with breaking things down phagocytise some bacteria, absorbing amino acids, secreting enzymes and signaling if one is full or not. 30. Which of the following is not a cellular component of the small intestine? A. goblet cell B. paneth cell C. fibroblast cell D. enteroendocrine cell E. absorptive cell Review: molecular detail- A fibroblast is responsible for synthesizing the extracellular matrix and collagen. They play a critical role in wound healing. 31. The functions of the lumen of the gut include... A. Enzymatic digestion at neutral pH B. Multiple defensive mechanisms C. Absorption of nutrients D. Both a. & c. E. All of the above Regulation: Molecular Detail The lumen is a simple columnar epithelium which functions to absorb nutrients, provide defensive measures via multiple mechanisms and enzymatically digest at neutral pH. 32. Which of the following is found in the crypts lining the digestive tract? A. rapidly dividing stem cells B. slowly dividing stem cells C. slowly dividing Paneth cells D. rapidly dividing Paneth cells E. b and d The stem cells undergo a slow cell cycle, whereas the Paneth cells are differentiated cells that are no longer dividing. 33. Stem cells differentiate into which cell types to form the lumen of the small intestine? a. Enteroendocrine cells & paneth cells b. Goblet cells & adsorptive cells c. Villus cells & goblet cells d. Both a. & b. e. Both a. & c. The small intestine is composed of 4 cell types all of which come from the same stem cell population. The 4 cell types include enteroendocrine (hormone), paneth (layer of cells beneath the stem cells in the crypt which is an immune cell), goblet and adsorptive cells. 34. If a cell wanted long term adhesion in the small intestine, it would need.....? A. Hemidesmosomes B. Desmosomes C. Adherens junctions D. Occluding junctions E. None of the above Due to the intermediate filaments, desmosomes would adhere a cell long term to the membrane of its target. Hemidesmosomes would adhere with anchor proteins to the basal lamina. Adherens junctions and occluding junctions are not long term, therefore, they are not the correct choice. 35. Which is true of tracheal epithelium? A. Ciliated epithelium B. Cilia moves in circular motion to get rid of debris C. Mucus traps dust and airborne microorganisms D. A and C are correct E. All of the above are correct The epithelium of the trachea is ciliated and mucus traps dust and airborne microorganisms, however, the cilia move in a wavelike motion, not in a circular pattern. 36. Which of the following best describe Trachea? A. Ciliated pseudostratified columnar epithelium B. Simple squamous epithelium C. Stratified squamous epithelium D. Simple columnar epithelium Rationale: The use of ciliated pseudostratified columnar epithelium is that it filters out debris and with the help of mucous secreted by goblet cells, traps and toss out bacteria and dirt junk. 37. The skin is... A. A stratified squamous epithelium B. A stratified squamous connective tissue C. A simple squamous epithelium D. A simple squamous connective tissue E. A simple columnar epithelium Regulation: Big Idea The skin is an stratified (layered) squamous (flat) epithelium. The primary function of the skin is to act as our primary barrier to keep unwanted things out. 38. What is the primary function of the Simple Squamous Epithelium in the blood vessel? A. It acts like protective physical barrier ( This is done by Stratified Squamous Epithelium) B. Absorption ( done by Simple Columnar Epithelium) C. Gas exchange D. None of the above (Has gaps to allow for gas exchange while adhering the blooed vessel together from collapsing) 39. Which of the following tissue is thin and specialized in ion and diffusion of gas? A. Connective tissue B. Simple columnar epithelium C. Simple squamous epithelium D. Cuboidal epithelium E. None of the above Rationale: connective tissue has a diverse properties and features, simple squamous are delicate and allow gases to be exchange across air sacs or lung. 40. What is a true statement about mesenchymal cells? A. They can differentiate into immune cells. B. They must adhere to epithelial cells to survive C. They are similar to epithelial cells D. They must adhere to their extracellular matrix E. None of the above Mysynchymal cells can differentiate but not to immune cells. They usually differentiate to a variety of cell types that includesosteoblasts (bone cells), chondrocytes (cartilage cells), myocytes (muscle cells) andadipocytes (fat cells). These cells then make help up our connective tissues.Mesenchymal cells are not like epithelial cells. Epithelial cells must adhere to each other to function properly. Mysynchymal cells must bind to their matrix to survive. So the correct answer is D. 41. Mesenchymal stem cells are a continuous source of A. Adipocytes B. Chondrocytes C. Osteoblasts D. A and B E. All of the above Section 4 A. Vertebrate cells in the context of tissue and organ architecture. Regulation: Molecular detail. The answer is e because mesenchymal stem cells are multipotent stem cells that can differentiate in a variety of cell types including osteoblasts, chondrocytes and adipocytes. 42. Which of the following is not made by fibroblast? A. nervous tissue B. loose connective tissue C. dense regular connective tissue D. elastic connective tissue The answer is A. Fibroblast is the origin of many mesenchymal cells and connective tissue. These include osteocytes, chondrocytes ,and adipocytes. 43. How is fibroblast different from mast cell? A. Fibroblast is a non fixed cell that can easily detach and move around B. Fibroblast produces fiber by secreting protein into the matrix of connective tissue C. Fibroblast is a fixed cell that releases histamine and heparin D. b and c E. a and c Rationale: fibroblast is a fixed cell but mast cell which is also a fixed cell releases histamine and heparin not fibroblast. While macrophages are the non fixed cells that can easily detach and move around. 44. In bone formation: A. Chondrocytes build cartilage models to begin bone formation B. Osteoblasts undergo hypertrophy, calcify and die C. Osteoclasts are involved in building of the bone D. Osteoblasts are involved in tearing down of the bone E. All the above During bone formation the bone starts out as cartilage models built by chondrocytes. So A would be the correct answer. B is false because it is chondrocytes not osteoblasts that undergo hypertrophy, calcify and die. BC and d are false because it is the opposite. Osteoblasts are involved in the building up or formation of the bone while osteoclasts are involved in tearing down of the bone tissue. 45. What are the functions of Osteoblasts and Osteoclasts respectively? A. Osteoclasts are the buildings of bone were as Osteoblasts are the demolition of the bone. B. Oesteoblasts are building of the bone and Osteoclasts are the demolition of the bone. C. Oesteoblasts and Osteoclasts are both the immune cell type of the bone derived from monocyte. D. None of the above (Only Osteoclasts is a Monocyte derivative that acts like the immune cell type of the bone were as Osteoblasts are mononucleate cells that are responsible for bone formation, Osteoblasts are specialized fibroblasts that in addition to fibroblastic products, express bone formation) 46. What is it that bone has that cartilage does not? A. Calcium apatite B. Proteoglycan C. glycosaminoglycan D. fibrous protein E. All of the above Rationale: Bone has all four components AND calcium apatite which allows it to harden. 47. What is the process by which bone is created using a cartilage model? A. cartilage model – chondrocytes hypotrophy – osteoblasts add calcium to ECM – osteoclasts finish up by removing bone tissue B. cartilage model – chondrocytes hypertrophy – osteoclasts add calcium to ECM – osteoblasts finish up by removing tissue C. cartilage model – chondrocytes hypotrophy – osteoclasts add calcium to ECM – osteoblasts finish up by removing tissue D. cartilage model – chondrocytes hypertrophy – osteoblasts add calcium to ECM – osteoclasts finish up by removing tissue Answer: D, the cartilage model is created by the chondrocytes, which undergo hypertrophy and eventually die. Their death is also attributed to the osteoblasts, which secrete calcium into their extracellular matrix to form the bone. The process is finished up by the osteoclasts removing and reabsorbing bone tissue that is not needed. This question is regulation: molecular detail, in that is goes through the molecular steps in creating bone from a cartilage model. 48. The adipocyte cell is derived from what cell? A. fibroblast-like precursor B. mesenchymal stem cell C. fibroblast D. goblet cell E. both a & b Adipocyte cells are derived from fibroblastlike precursor cells which are a type of mesenchymal stem cell. 49. The overlapping stages of wound healing in order are… A. Hemostasis, inflammation, proliferation and maturation B. Hemostasis, proliferation, inflammation and maturation C. Apoptosis, proliferation, maturation D. Proliferation, apoptosis and maturation E. Proliferation, inflammation and maturation The first stage of homeostasis includes vasoconstriction, platelet aggregation and thromboplastin makes clots. In the inflammation phase vasodilation and phagocytosis occurs. In the proliferation phase granulation, contraction and epithelialization occurs and maturation is the remodeling phase when the new collagen forms leaving scar tissue weaker than the original tissue. Therefore all other answers are incorrect. 50. Inflammation is a process mediated primarily by WBC as part of our_____. A. Adaptive immunity B. Innate immunity C. Acquired immunity D. Natural immunity Innate immunity refers to antigen-nonspecific defense mechanisms that a host uses immediately or within several hours after exposure to an antigen. This is the immunity we are born with and is the initial response by the body to eliminate microbes and prevent infection [5]. 51. What is the main factor involved in causing vasodilation during the inflammatory phase? A. Serotonin B. Histamine C. Prostaglandin D. Prostacyclin E. Bradykinin A5.’B’; Platelets also release other proinflammatory factors like serotonin, bradykinin, prostaglandins, prostacyclin’s, thromboxane, and histamine, which serve a number of purposes, including to increase cell proliferation and migration to the area and to cause blood vessels to become dilated and porous.Vasodilation is the result of factors released by platelets and other cells. The main factor involved in causing vasodilation is histamine [1][2]. Histamine also causes blood vessels to become porous, allowing the tissue to become edematous because proteins from the bloodstream leak into the extravascular space, which increases its osmolar load and draws water into the area. Increased porosity of blood vessels also facilitates the entry of inflammatory cells like leukocytes into the wound site from the bloodstream [3][4]. 52. Which step in wound healing is responsible for stimulating cells to fill in the wound? A) Inflammation B) Hemostasis C) Maturation D) Proliferation Answer D, because hemostasis stops blood flow by forming clots, inflammation initiates swelling, redness, and pain and is the most important step to wound healing, and maturation remodels, so original functions can be restored as much as possible. Proliferation stimulates cells to fill in the wound by migrating across fibrin which is a temporary ECM to allow cells to grab on to something in order to migrate and start to heal the wound. 53. What are require for the formation of the scar matrix?\ A. Glycosaminoglycans B. Proteoglycans C. Fibrous proteins D. Elastic proteins E. All of the above Rationale: glycosaminoglycans consist of almost everything of the ECM. Proteoglycans organize the ECM sugar and gives structure. Elastic proteins are require for flexibility. Fibrous protein may be used for constructing connective tissue, tendons and bone matrix.